Stereoselective synthesis of optically active 2-hydroxymandelic acids and esters via Friedel-Crafts coordinated reaction:: Crystal structure of chiral dichloro[2-(1-oxido-1-menthoxy-carbonylmethyl)-4-methoxyphenoxido-O,O,O]titanium

Highly diastereoselective hydroxyalkylation of phenols with chiral glyoxylates was performed. Hydrolysis or reduction of the esters 3 afforded 2-hydroxymandelic acids 6 and diols 5 in high yields and enantiomeric pure form. Mechanistic evidence of chelation-controlled reaction comes from the crystal structure determination of titanium phenoxide complex 8.